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In this photo provided by Korea Coast Guard, the Panama-registered tanker "Sanchi" is seen ablaze after a collision with a Hong Kong-registered freighter off China's eastern coast Sunday, Jan. 7, 2018. The oil tanker collided with a bulk freighter and caught fire off China's eastern coast, leaving its entire crew of 32 missing, most of them Iranians, authorities said.

An explosion rocked a stricken oil tanker off the coast of Shanghai on Wednesday, forcing maritime authorities to suspend firefighting and rescue efforts, Chinese officials said.

China's ministry of transport said rescue vessels withdrew to a safe distance after the explosion on the Sanchi's bow, the latest setback in the multinational effort to extinguish the burning wreck and find more than 30 missing crewmembers.

The ship is still on fire, the ministry said.

Chinese officials have previously warned that the tanker could explode and sink, possibly triggering an environmental disaster.

The Sanchi was carrying nearly 1 million barrels of condensate, a type of gassy, ultra-light oil, when it collided Saturday evening with a freighter 257 kilometers (160 miles) off the coast and caught fire. Intense flames, bad weather and poor visibility have hampered rescue efforts.

The entire crew of the Panamanian-registered Sanchi — 30 Iranians and two Bangladeshis — went missing after its collision with the Chinese freighter CF Crystal. The cause of the collision remains unclear.

Rescuers on Tuesday found a body believed to be a sailor from the Iranian-operated tanker, while a search continued for the 31 other missing crew members.